A level Biology: Post your doubts here!

[Rizwan Javed]

Can someone please explain this question? Answer is C
View attachment 60214

CO2 binds with haemoglobin at terminal -NH2 groups, forming carbaminohaemoglobin. Whereas oxygen binds with haem groups containing Fe+2. CO also binds with haem group, as you know that it's binding reduces the affinity of haemoglobin for oxygen (thus an indication that CO and O2 have similar binding sites).

Hence the answer is C.

 

[princess Anu]

View attachment 60211
mp6 not clear what does it mean meiosis complete

Remember the oocyte doesnot complete its division uptil fertilisation
Every month the primary oocyte completes its 1st meiotic division to form a secondary oocyte
But this secondary oocyte is arrested in metaphase II
It'll only complete meiosis II when fertilisation occurs

 

[Mahnoorfatima]

Question 4 part c and d anyone? A2

 

[Mahnoorfatima]

What at the advantages of increased number of synapses? I get that a wider range of responses can be generated but how do I explain it?

 

[Mahnoorfatima]

Is this in our course anymore??

 

[mohmed ahmed soliman]

IN MS they write for artificial selection question avp eg. any detail of breeding technique
help me to write anything for this

 

[mohmed ahmed soliman]

describe how resting potential is maintained across the axon membrane
12. idea of leaking k ion is responsible for resting potential
13.electrochemical gradient

what does this MS points mean i thougtt that resting potential was caused by na-k pump puming 2k ion in while pumping 3 na ions out so this unfair pumping resulting in resting potential

 

[mohmed ahmed soliman]

what does local circuit means they always mention it in MS in how impulse in conducted along a neurone or descibe how action potential occurs

 

[Mahnoorfatima]

describe how resting potential is maintained across the axon membrane
12. idea of leaking k ion is responsible for resting potential
13.electrochemical gradient

what does this MS points mean i thougtt that resting potential was caused by na-k pump puming 2k ion in while pumping 3 na ions out so this unfair pumping resulting in resting potential

Because the axon membrane has more protein channels for potassium than for sodium therefore it's natural for some potassium ions to diffuse out faster than sodium diffuses in. But at the same time there are many negatively charged molecules inside the cells of the axon that attract K+. This REDUCES the chance of K+ ions diffusing out

 

[Mahnoorfatima]

Why does the carbohydrate content of a seed increased when the outer layer of the seed is removed? Is it because the starch cam no longer be hydrolysed into maltose and glucose as the aluerone layer of the seed contains amylase which is activated by GA in the embryo which is also removed??? And where is fibre present in a seed?

 

[mohmed ahmed soliman]

Why does the carbohydrate content of a seed increased when the outer layer of the seed is removed? Is it because the starch cam no longer be hydrolysed into maltose and glucose as the aluerone layer of the seed contains amylase which is activated by GA in the embryo which is also removed??? And where is fibre present in a seed?

i think because suppose carbohydrate represents 60% of mass of a seed but when outer layer is removed , the carbohydrate will represent even a higher percentage of 80% of seed mass

 

[Eugene99]

can anyone please explain this? how changing gases can affect diffusion or active transport rate?

 

[Rizwan Javed]

View attachment 60240
can anyone please explain this? how changing gases can affect diffusion or active transport rate?

Is it C? :3

 

[Eugene99]

Is it C? :3

yah

 

[Rizwan Javed]

yah

Oxygen is required for aerobic respiration. Aerobic respiration results in formation of ATP which is utilised for active transport of substances. You can see that the graph of 3 carbon sugar remains unchanged that means that the transport of this sugar is not active rather passive. Whereas 6 carbon sugar is not transported in absence of oxygen (graph 2), which shows that its transport is active.
Therefore C.

 

[Eugene99]

Oxygen is required for aerobic respiration. Aerobic respiration results in formation of ATP which is utilised for active transport of substances. You can see that the graph of 3 carbon sugar remains unchanged that means that the transport of this sugar is not active rather passive. Whereas 6 carbon sugar is not transported in absence of oxygen (graph 2), which shows that its transport is active.
Therefore C.

thanks

 

[osama ahmed ibrahim]

in learning it is believed that number of synapse between brain and eorone increase
suggest and advantage for this increased number of synapse
allows more interconnection of nerve pathways / AW ;
2. for, memory / AW ; ignore learning
3. allows wider range of responses ;
4. AVP ; e.g.

summation?

allows wider range of responses ; how

llows more interconnection of nerve pathways / AW ; what does this mean

 

[Shah34]

Guys plz help
Q25)A
Q19)C
Q23)A

 

[My Name]

Guys plz help
Q25)A
Q19)C
Q23)A

I think this is how it is.
15 base pairs long.
Add up whta they've given you, 6+3+4=13.
What's left is for Guanine,so 15-13=2.
So A.

 

[techgeek]

Guys plz help
Q19)C

Chromosomoes appear as two chromatids during prophase and metaphase, so 73+16 since total there are 1000 cells
percentage will be 89/1000 x 100 =8.9%